EPJ Web of Conferences (Jan 2017)

Advanced electron cyclotron heating and current drive experiments on the stellarator Wendelstein 7-X

  • Stange Torsten,
  • Laqua Heinrich Peter,
  • Beurskens Marc,
  • Bosch Hans-Stephan,
  • Bozhenkov Sergey,
  • Brakel Rudolf,
  • Braune Harald,
  • Brunner Kai Jakob,
  • Cappa Alvaro,
  • Dinklage Andreas,
  • Erckmann Volker,
  • Fuchert Golo,
  • Gantenbein Gerd,
  • Gellert Florian,
  • Grulke Olaf,
  • Hartmann Dirk,
  • Hirsch Matthias,
  • Höfel Udo,
  • Kasparek Walter,
  • Knauer Jens,
  • Langenberg Andreas,
  • Marsen Stefan,
  • Marushchenko Nikolai,
  • Moseev Dmitry,
  • Pablant Novomir,
  • Pasch Ekkehard,
  • Rahbarnia Kian,
  • Mora Humberto Trimino,
  • Tsujimura Toru,
  • Turkin Yuriy,
  • Wauters Tom,
  • Wolf Robert

DOI
https://doi.org/10.1051/epjconf/201715702008
Journal volume & issue
Vol. 157
p. 02008

Abstract

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During the first operational phase (OP 1.1) of Wendelstein 7-X (W7-X) electron cyclotron resonance heating (ECRH) was the exclusive heating method and provided plasma start-up, wall conditioning, heating and current drive. Six gyrotrons were commissioned for OP1.1 and used in parallel for plasma operation with a power of up to 4.3 MW. During standard X2-heating the spatially localized power deposition with high power density allowed controlling the radial profiles of the electron temperature and the rotational transform. Even though W7-X was not fully equipped with first wall tiles and operated with a graphite limiter instead of a divertor, electron densities of n e > 3·1019 m-3 could be achieved at electron temperatures of several keV and ion temperatures above 2 keV. These plasma parameters allowed the first demonstration of a multipath O2-heating scenario, which is envisaged for safe operation near the X-cutoff-density of 1.2·1020 m-3 after full commissioning of the ECRH system in the next operation phase OP1.2.